Classification



sePf- 19, 1944. A. w. AHRENWALD Re. 22,546

CLASSIFICATION Original Filed latch 6. 1940 4 Sheets-Sheet 1 n. N." om,... m

ATTORNEY.

Sept. 19, 1944. A. w.FAHRr-:NwAL.D

CLASSIFICATION Original Filed March 6. 1940 4 SheetsSheet 2 ATTORNEY.

A. W. FAHRENWALD Sept. 19, 1944.

CLASSIFICATION 4 sheets-sheet :fi

Original Filed March 6. 1940 INVENTOR ATTORNEY.

SePt- 19, 1944. A. w. FAHRENWALD I Re. 22,546

CLASSIFICATION origial Filed March s, 1940 4 Sheets-Sheet 4 ATTORNEY@ 1 e referred to as slimes.

Remued'sept. 19,1944

'.,UNiTED STATES ini-'islsrl"v oFFlcl-z' 'CLASSIFICATION Arthur wuuam nimm-ua, Moscow, nino, sa.

signor to The Dorr Company, Inc., Newr York, N. Y., a corporation of Delaware original No. 2,301,931, latedv November 17, 1942, seri-1 No.. 322,455, Maren s, 1940. Application for reissue January 22, 1943, Serial No. 473,233

. 9 Claims. (Cl. 209-423) The invention relates to process of and `apparatus for the hydraulic separating, classifying or fractionating of pulp bearing different-types of solids of uniform or -even different sizes, or bearing solids ofV the same type but of different sizes. or bearing mixtures of the foregoing; such a pulp is exemplified by what is known as metallurgical pulp.or that which may be knownas pulp because of the solids including miscellaneous mixtures such as earth bearing materials in- -cluding gravel, ,clayl or the like. wherein Vthere hydraulicpassing'offtlielargergorfmore readily t which liquid with une particles therein lmisses as` slimes.- -v Provision tis-madezforuan ontowg or settleable type of solids from the bottom of the body as and' when an unbalanced condition is f created or becomes established suiilcient` to cause such outflow because 'of a building'up of solids y are included relatively large or quickly settleable.

solids frequently referred to as sands or concentrate andY light `or fine particles of a character less readily settleable-or which are settleable only with ditliculty or even after special preparatory treatmentand which pass olf as suspended solids in the o utowing liquid in a form of liquid-solids mixture which is commonly The process or apparatus is also applicable to the treatment of metallurgical pulps bearing relatively heavy metallic particles such as gold and which particles although small, are more .readily `settleable than the sand in which they .are found or exist. y

An object of the invention is lto provide a process of and for the fractionating of pulps or mixtures of readily settleable solids and solids which are not readily settleable whereby for the ,performingof the process there may be employed apparatus/which is relatively small in size and eillcient and effective in operation as compared with the present-day. apparatus.

I have developed a novel process and appa-- ratus of a continuous mode or type which for the performance and operation thereof is based upon the fact that a liquid-solids body of' pulp Y may be established in a'ciassifying zone or area and be maintained thereinin a condition in which the settled solids and that section of the liquid in` vwhich they are primarily found constitutea mobile mass which is attainable and realizable by the proper actuated movements imparted to underlying constriction member having numerous discharge openings or orifice t portionsfroi which water is forcibly discharged upwardly into `the overlying liquid solids body in quantities sumcient for realizing the desired classifying operation. l

' According tothe process and apparatus the liquid-solids body wherein the mobile mass 4is caused to exist is continuously supplied with pulp fed thereto, it is maintained at arelatively .constant level because of an oterflow Weir over and increase' of density within the body sufiicient to overcome `a relatively constant back pressure which is provided. and maintained for preventing an outflow of solids except when such unbalanced conditions exist at the outflow region leading from the lower portion of the body. In

this connection'it will be noted that in the performing of the process and inoperating the apparatus there is employed means for insuring a constant back pressurewhich can be relied upon for balancing the hydrostatic pressure or static head at the bottom or lower portion of the liquidsolids body except when incident to and following the feeding of pulp to the body there is realized the increase in the density and solids loading of the body with a consequent pressure venience, but they are intended to be as generic in their application to similar parts as the art will permit. In the accompanying drawings there has been illustrated the best embodiment known to me, 'but such embodiment is to be ref garded as typical only of many possible embodiments,v and the invention is not to Abe limited thereto.A

Reference is nowmade to said accompanying drawings which form a part of this specication.

In said drawings- Fig. l is a 'plan view of one form of apparatus for realizing the invention hereof; in this figure certain parts' are shown broken away whereby certain other parts lappear either in horizontal section or in plan; l

Fig. 2 is a vertical sectional view of the apparatus taken as on the planes indicated by the broken line 2-2 of Fig. 1 looking in the direction of the arrows; this Fig. 2 for convenience is referred to as a vertical longitudinal sectional view;

Fig. 3 is a transverse vertical sectional view taken as on the plane indicated by the line I-I of Fig. 1 looking in the direction of the arrows;

Fig. 4 is a view diagrammatically illustrative of features of certain operating parts of another form of apparatus by whichthe invention may be realized.

The embodiment illustrated by Figs. l,- @andl .sans

ilnes the outermost limits or boundary of the liquid-solids body.

Main frame The main frame includes longitudinally-extending beamsv or longitudinal channel members 2, transversely-extending headers or transverse channel members l and motor supporting platllo 3 hereof represents that which is considered as' indicativeV of a. preferred form of apparatus as` developed by'fme, but it is to be understood that according to the fundamental and basic aspects of this invention, the process hereof ycan be realized in diverse manners. and the apparatus hereof can be embodied in diverse forms while still continuing to be within and spirit of the invention.

General A main frame I is provided as the main support for the classier '2| or classifying element proper. Upon this frame there is vmounted suitable xiiotivated mechanism for imparting reciprocatory movement to said classier or to at least y some member thereof.

In each form of classifier illustrated there is a funnel-shaped member 23 underlying an apertured ow constriction member or plate as 24 (see Fig. 3) of relatively .constant elevation and a cylindrical wall 32. Within the funnel-shaped member 23 and below the constriction member 24 there is provided a space 25 sometimes referred to as a hutch compartment or zone within which water under pressure is received initially. Within the cylindrical wall 3-2 and immediately overlying the ow constriction plate there is provided a classifying space or zone 42 wherein a liquid-solids body undergoing classiiication is maintained at an operative level normally determined by an overflow weir 34 l (Fig. 3) of relatively constant elevation which is sometimes identied as a. high or slimes weir. Water supplied under pressure to' the hutch compartment 25, is forcibly passed upwardly through relatively uniformlyspaced orifices 38 in that area of the constriction member 24 that com'- -v prises the lower limits orboundary of the liquidsolids body or the classification zone 42 that holds that body. The water is delivered upwardly into the lower portion ofthe liquid-solids body immediately voverlying the orifice section. An important feature of the present invention revolves about a movement of the flow constriction member in'a repetitive manner whereby there is attained an intimate and relatively uniform dis` persion of Athe upowing Aliquid within and throughout the liquid-solids body undergoing classification; and also a tangential type of engagement by the supporting surface portion of the flow constriction member with the solids in the lower portion of the body wherein mobile characteristics are imparted to a. mass of suspended solids in the liquid, particularly 'in the lower portion of theliquid-solids body.

A motivated mechanism is therefore provided for imparting the requisite repetitive movement to the flow constriction member which movement according to the form of apparatus illustrated is a back and`forth horizontal oscillatory movement within a relatively small arc about a verticallyextending axis that is concentric with the hollow cylinder or circular wall I2 that marginally dethe purview f form -4. The frame also includes necessary tie plates as 5 and diagonal bracing elements or members as. 6 all of which are suitably connected as' by bolting, riveting or welding so as to form a relatively self-contained, rigid and strong sup- Jporting structure or base member.

Motivated actuating mechanism A motor 1 is securely mounted upon the platform 4 and it provides a driving pulley 8 which in turn transmits through the medium of`a belt 9 power to a driven pulley III secured to a horizontally-extending crank shaft Il'. This" crank shaft ll is mounted in horizontal bearings or ,pillow blocks I2 suitably secured to or supported on the main frame. The crank I3 of the crank shaft Il has connected thereto so as to be actuated therefrom end I4of a connecting rod I5. 'I'he other end IB of the connecting rod is referred to as the classifier end and is suitably connected at and to the outer end portion Il of an arm 22 extending from some part of the classiiler or to some member of the classifying construction carrying or having driving connection y with the ilow constriction member.

In theconstruction shown, the classifier end IB of the connecting rod I5 has operative engagement with the outer end I1 of the arm 22 extendingfrom the funnel-shaped member 23 which in turn can'ies the flow constriction plate 24 as is clear from an inspection of Fig. 3. It will hereinafter be made apparent that this arm 22, and the member by which it is carried or from which it extends, has imparted thereto back and forth oscillatoryI movements in horizontal directions ,about a 'vertically-extending axis, or as otherwise expressed, repetitive oscillatory movement of relatively limited arcuate range in a horizontal path. `This repetitive movement is provided essentially for imparting the required movement to the constriction plate 24; (a) whereby the upflowing water hasmore uniform dispersion within and throughout the liquid-solids body; Aand (b) whereby the longitudinal engagement between the upper surface of the plate and any solids touching it will further the maintaining of the desired mobile characteristics of the aquila-solids mass. Any suitable construction may be used for operatively associating the end I6 of the connecting rod with the outer end I'l-of the arm 22. In the construction shown the outer end of the arm 22 is provided with oppositely -disposed curved surfaces I 8 and an opening o for the reception ofthe end I6 of the connecting rod I5. It hwill be noted that the connecting rod end I6 is screw threaded andl that upon this section there are located positionable washers or intermediate` blocks I8 in the form of bearing members disposed for engaging the curved "surfaces I8. These washers are normally held in place in adjusted position by nuts 20. ,y

From what has preceded, particularlyin con-` nection with the drawings, it will be readily apparent how and why the motor actuated kniechanism functions to impart repetitive movement of the desired character to the flow constrictio platre. y n

Classfleror classifying element Proper f Figs. 1 to3 .porting structure, and provides astationary or xed supporting main bearing for a movable bearingmember21.`

A movable bearing member 21 is mounted in the stationary bearing 29 in a manner whereby the movable lmember 21 and the parts supported therefrom and movable therewith, can have repetitive horizontal turning movementimparted 'Y jthereto through the medium of the actuating mechanism heretofore referred to. In order to provide for ease ofmovement. an anti-friction 'type of bearing construction 28 or anti-friction n the stabers 2i and 21 respectively. ,y l.:

'I'he upper end of the'movable bearing member l l21 isprovided with a`flange 29 andreceiv'esthe lower end 30 of the funnel-shaped member 23 that provides therein thesection ofthe classi- 11er which is frequently referred to as a hutch compartment and which as previously indicated is immediately below the `apertured flow constriction plate 24. The funnel-shaped member 23, as the name implies, is in the form of a truncated base portion of an inverted cone and the lower` or small end 3II thereof is rigidly connected' in any suitable manner to the ange 29, in fact, astrong and water-tight joint isprovided between them.v

` The upper or large end of the funnel-shaped member 23 is provided with a ange 3|. The

lower end of the hollow cylinder 32 is provided terpositioned margin of the flow constrictionl plate 24. In order to prevent leakage through or past the bolted joint construction just referred to, suitable packing material or gaskets are provided atA 35. The upper end of the circular marginal wall 32 is horizontal and provides at 34 that which may be referred to as a high slimes overflow weir of relatively constant elevation that determines the normal operative level of a liquid-solids body which is defined as to its outer marginal limits by the circular or cylindrical wall 92 and as to its lowermost limits by the flow constriction plate 24.

` discharge section 31 leading'from the classifier.

As to the iiow constriction member 24 this is shown as a horizontallyfextending flat plate and comprises an apertured portion or apertured .general section in which there are relatively small liquid upflow openings 3l that are disposed in a relatively uniform` or systematic manner sans During the normal operation of the classifier liquid with the less throughoutk the yarea or regions thereof immediately underlying the liquid-solids body undergoing solidsr fractionating or classifying treatment Ain the classifying zone of the classier, to wit, in theannular space orzone 42.

The circular marginal wall 22 providing the slimes overflow weir 34 of relatively constant ele' Vvation,rthe now constriction plate oriapertured part of a unitary structure supported for repeti-4 tive horizontal back and" forth movement, that is,

for horizontal back and forth oscillatory movement about a vertical axis and in a manner whereby no substantial vertical movement is imparted to said unitary structure and of which each -member will consequently remain at substantial constant elevation, thereby avoidingany bodily *raising or lowering of the liquid-solids body overlying the apertured constrictionrplate "and located within the marginal wall 32. In

er,v words, the slimes overflow weir functions s Vvnstiirit#elevationJl'aidtliesowi'coristriction 2'5 I n i foscillatedfinfhorizontal paths"about"a1vertical'axis'while always continuing atsubstantially the same operative elevation without havingany vertical movement imparted thereto. It will also be notedl that the hereinafter referred to inwardly disposed cylindrical member or baille 40 and an inwardly disposed cylindrical member 63 having associated therewith adjusted low solids weir 16 hereinafter referred to constitute part of the oscillatable unitary structure and said low solids overflow Weir 'Is when adjusted constitute low sands overow weirs substantially at constant elevation.

The flow constriction member 24 which is shown horizontally extending nat plate is some- 40 times herein properly `Vreferred to as a constriction plate having a level upper surface. It is l proper also to refer to this constriction plate as an oriiiced flow distributing fiat plate The classier is constructed-so as to provide for the autnatic discharge of the more readily settleable solids during the period of normal operation of the classifier consequent to a feed of pulp thereto to be treated and to that end there is embodied in the classifierconstruction means providing a solids discharge area or passageway leading from the lower portion of the liquid-solids body in the classifier, to wit, from the lower interior portion of the classifying zone A42 to a region in which the solids conveyed therethrough are distant f rom the classifying zone or space 42. To provide such means the classiferof Figs. 1 to 3 is constructed so as to include a baille member below gir-through which there is provided a solids discharge passageway or area and also so as to include means providing a damor low overow Weir construction. In the embodiment of said Figs. 1 to 3 the b aflie member is cylindrical in horizontal cross section ands provided by an inwardly disposed cylindrical mem o5 ber 40 which extends downwardly from an elevation somewhat higher than thatv of the normal surface level lof the liquid to a locality close to but vertically-spaced above the apertured flow constriction member24- whereby thel solids discharge area or passagewaylis provided for or left at 4l for the passage thereinto and therethrough of certain quantities of the concentrates or .larger or more readily settleable type of solids in said Figs. 1 to 3 inclusive this baille member 4I extends all the way down to the flow constriction plate 24 except for the discharge area or open sections left at 4I. As part of the solids discharge means there is also included an innermost cylindrical member 43. This is connected to the now constriction plate 24 as by ymeans of the bolts 44 and extends upwardly therefrom. This member 45 is constructed to provide openings or passage area at 45 through which solids can pass incident to their overowing verticallyadjustable weirs 16. The weirs 14 are herein referred in as the low solids overilow weirsand it will be noted that they are disposed at elevations lower than that of the higher or slimes overflow weirs 34. The weirs 18' are provided by and at the upper edges of curved plates 11 that substantially nt the juxtapositioned contour of the cylindrical member 4I. These curved plates have vertical edges that are disposed so as to have sliding engagement in vertical guide-ways provided at 1l. These plates 'I1 may be vertically positioned to attain any desired operative elevation for the overflow weirs 18 thereof through the medium of screw-threaded vertically-extending rods .19 and the cooperating hand-wheels or nuts 80 which have bearing portions Ii that derive support from the horizontal feed distributing plate 52 and which are turnably held thereupon by the retaining rings l2. The weir 16 when in adjusted normal operative position functions substantially as a low sands overflow weir of constant elevation. In the construction shown the cylindrical baille member 40 is directly secured to the cylindrical low weir providing member 4l in any suitable manner as by means of brackets or connecting braces 45. 'I'he result of the construction described is that the outermost or cylindrical marginal wall l2, the cylindrical baille member 4B and the inner cylindrical low Weir providing member 4I all have the same angular oscillating movement imparted thereto as thatwhich is imparted to the funnel-shaped member 2l, and thereby to the flow constriction plate 24.

The central section 4l of the flow constriction plate 24 is solid or imperforated except for the central discharge opening 48 provided for the down passage of the heavier larger solids, to wit,

'the sands or concentrate which are discharged therefrom into and downwardly through a depending sands discharge pipe or conduit 55.

The inner cylindrical member or low solids overflow providing plate 43 has a relatively water-tight bolted connection with the central section 41 of the flow constriction plate whereby a sands receiving space is provided at 49. Th pipe or conduit 55 has a water-tight connection at 55 to the imperforated central section 41 whereby there is avoided the leakage of pressure water from the hutch compartment 25 into the sands receiving space 49. The pipe or conduit 55 passes downwardly through the movable main bearing 21 and is provided whereby sands can'freely pass from the sands receivingA space 49 to a region outside of or remote from the classifier. Suitable provision is made, to witl such as is accomplished by packing material as at 51 for preventing the outflow or escape of pressure water from between the exterior of the conduit 55 and the movable bearing 21 through which it extends.

It'has been pointed out that theu liquid-solids body undergoing treatment is dened as to its outermost marginal limits by the cylindrical marginal wall 32. As to its innermost limits it is defined by the cylindrical baille member 40.

The membersor parts 32, 24 and 45 just referred to delineate or outline the space or zone -which has been designated as 42 and which has herein been referred to as the classifying zone. In this zone there is maintained a liquid-solids body of constant volume but in which the specific gravity or effective hydrostatic'pressure head at the bottom is changeable as according to changing rates `comprehends a small hopper 50 which is vsupt ployed the'funnel-shaped hutch member 23 that v ported through the medium of horizontallyspaced legs 5| extending upwardly from a horizontal feed or pulp distributing plate l2 that is secured to the upper end of the cylindrical baille member 40 as by means of angle irons or brackets provided at 53. The outer edge portion 54 of this distributing member 52 is preferably at or proximate the normal surface level of the liquidsolids body inthe classiier whereby .the pulp dropping or'plunging therefrom for classifying treatment is discharged into the liquid-solids body without creating undue disturbance therein.

Reference has heretofore been made to the fact that the chamber 25 below the construction plate 24 and within the funnel-shaped m'ember 23 may be referred to as a hutch compartment. This same compartment 25 may be referred to as a pressure chamber wherein water is received that is supplied thereto through the medium of a tubular iiexible connection providedv at 59.

During the normal functioning of the machine water is supplied under pressure through this connection and forcibly upiiows from the constriction plate into' the lower portion of the liquid-solids body which is maintained within the fractionating or classifying zone 42 of the classifier.

In the instance of certain pulps very fine solids of heavy specic 4gravity pass downwardly through the orice portions of the constriction said compartment because of a passageway 58.

leading downwardly throughl the movable bearing member 21 and may be collected therefrom through the medium of a flexible connector provided at 59.

classifier of Fig. ,4 The form of apparatus typically illustrated by Fig. 4 follows the principle of construction already described in connection with'the form of apparatus illustrated by Figs. 1 to 3 inclusive but certain differences as to specific features thereofwill be apparent from that which follows:

According to the form of Fig. 4 there is emis mounted on the flange portion 28 of a movable bearingmember 8|, which is normally mounted on a stationary main bearing as 25 of Figs. 1 to 3 and in the same manner that the corresponding movable main bearing 21 of Figs. 1 to 3 is mounted. This hutch member also carries an apertured flow constriction plate $2 of substantially constant elevation and an outermost cylindrical wall 63 above the plate, all of which are suitably secured together as by bolts after the manner of the similarly shaped parts of the apparatus shown in Figs. 1 to 3.' Water is supplied under pressure as by the nexible connector, toA

ow weir of substantially constant elevation. l

This weir 64 is sometimes referred to asa low solids overflow weir and is at an elevation lower than that of the higher slimes overflow weir IB of substantially constant elevation. The cylindrical member 83 has vertically-extending slots or openings 84 for receiving bolts B5 thereby providing a construction arrangement by which vertical adjustment for the low slimes overflow weir 6I can be realized. The exterior A Ioi' the positionable cylindrical member 8! is such as to substantially t the interior of the outermost cylindrical wall 63 and when secured in placeby the bolts 85 in effect becomesan extension or part of the marginal wall of which the outer cylindrical member 63 constitutes a part.

A second cylindrical member 65 which is inwardly and concentricaliy disposed with respect to the cylindrical member 63, is fixedly secured tothe latter through the medium of horizontallyspaced brackets or supports 60 whereby it is ilxedly positioned with respect to the cylindrical member 63 an'd the underlying constriction plate B2. This second cylindrical member B5, however,

extends to an elevation higher than -that-of the outer cylindrical member 63 and is provided at and along the upper margin thereof withan overflow weir 66 which is sometimes herein referred to as a high slimes overflow weir, From the drawings it will be noted that the slimes overflow weir 66 is at an elevation higher than that of the solids overflow Weir 6l The cylindrical member 65 extends downwardly to regions proximate the perforated plate, in fact, it is feasible to extend parts thereof all the way down to said perforated plate. However, there are provided or left in or below the lowermost portion thereof solids discharge area or passageways 61 leadingy from the lower portions of the interior section providing the classification zone 68 to the exterior of the classifyingi space, or what is the same thing, to a region that is exteriorly located with respect t-o'the liquid-solids body that is maintained in the classifying zone 68. The cylindrical wall 85 marginally defines the outermost limits of classifying space wherein the liquid-solids body is located while undergoing the fractionating treatment.

The apertured flow constriction plate B2 has connected thereto a small innermost cylindrical construction or column 69 concentric with'the marginal cylindrical wall 65 just referred to. This smaller cylindrical member or column constitutes a support at the upper portion of which there Ais carried axfeed distributing plate 'III which in turn supports a feed hopper construction 1| similar to that employed in connection with the form of apparatus shown in Figs. 1 to 3.` In the instance of the construction of Fig. 4 wthe movable bearing member BI is provided with only one opening extending downwardly therethrough,

namely, openinfigi` l!` for the delivery therethrough of the hutch products and from which there extends a flexible hutch delivery pipe or conduit 1I that is connected L'y coupling 13 to the lower lend of the movable bearing member 6| I In the in-- Operation of the apparatus The expression "pulp as employedherein implies any liquid containing suspended solids of diil'erent sizes of which the larger sizes are more 5 readily Settleable than are the smaller sizes. This expression may also comprehend liquid containing suspended solids o1' which some are of a type `that are more readily settleable than others because of a difference in the specific gravity of the of which have different specific gravity from others and some of which have different sizes as compared with others with the result that some of the solids are readily settleable while others l5 are less readily settleable. Pulp also includes `that which is known as metallurgical pulp. It may include that which is a suspension of sand and ine clay. It may be a metallurgical type of pulp of which there are ne solids not readily settleable, of which there are coarse solids that are readily settleable and of which there are other solids in very fine sub-division or of small particle size which are more readily settleable than the large solids because of their much greater specific gravity as compared with that of the larger but less readily settleable solids. An instance of this is realized by the small gold particles in metallurgical gold bearing pulp.

`The material to be treated may be in relatively so dry form lbut when acted upon for classification, it must be in the form oi' liquid-solids mixtures, or` suspensions. The process hereof is one involving the separation of suspended solids by a hydraulic classifying operation into the morev readily settleable and the less readily settleable groups with the line of demarcation between the groups being controllable at will. In starting the operation, there is first established a liquidsolids body or suspension within a liquid-holding 40 or classifying zone of the classifier. 'I'his compartment is marginally definedv by a cylindrical wail of the classifier that has associated with it a perforated lflow constriction plate that defines the lowermost limits of the liquid-solids body.

The cylindrical baille member lil of Figs. 1 to 3 or the cylindrical central column 69 of Fig. 4

constitutes inwardly disposed members circular in cross section that in effect define the innermost limits of the classifying zone and of the 'liquid-solids body within said classifying zone. 'I'hus in each form, the classifying zone or area for the maintained liquid-solids body is comprised within the space between .the concentric hand. This classifying zone and its liquid-solids,

body is dened as to its lowermost limits by Athe flow constriction plate whose apertures or disglge orifices are directly below the liquid-solids Assuming that a liquid-solids body or suspension has been established within the classifying compartment and that the flow constriction plate is being reciprocated or oscillated so as to maintain the mobile lsuspension characteristics for` the solids within the liquid-solids body, then during the normal operation of the machine, there is provided a continual supply of water 7o vunder pressure into the hutch compartment so the constriction plate and enter in the form of jets the lowermost portions of -the liquid-solids body. 'I'he mechanism for imparting horizontal oscillating movement to the ilow constriction solids, or it may include suspended solids some that it can flow upwardly through the'oriilcesl of plate continues in operation. 'I'he repetitive back and forth movements of the horizontal constriction plate cause a tangential type of engagement between it and the heavier or settled solids in .the liquid-solids body as they drop or settle into contact therewith, with the result that there is a slight oscillatory movement imparted to these solids, of decreasing intensity with increasing distance from the plate so as to cause a relative movement of adjoining planes and a mutual rolling effect all resulting in imparting to the solids individual as well as group mobility. This mobile state or condition will continue to be maintained even though the supply of water iunder pressure should be temporarily cut of! and l to 3, or l1 lof Fig. 4, and whereby some of the solids which have heretofore passed the discharge openings or area will be elevated to a position within the space I9 which is immediately over even though there is no pulpfeed being introduced into the classier. Assuming. however, that water is being supplied under pressure to the hutch chamber so that it flows upwardly through the orifices as iets into the liquid-solids body and assuming that no feed is being introduced into the machine at that particular time', .then practically the sole result will be upilow and outow of liquid with only a relatively small amount of nes therein to and past the high slimes weir. There will be no appreciable outow of solids past the low weir because there is a substantial quantity thereof at the delivery side of the solids discharge area or openings, as Il of Figs. l to 3 and ahead of the low solids overflow weirs provided as by weir or weirs l! of the same gures. Such collection oi' the heavier settleable solids outside of the classifying zone is sufficient to impart a relatively constant density to the outside liquid-solids mixture comprising the same and. thereby there results a rela` tively predetermined constant back pressure that continuously functions to oppose the outflow of solids or liquid from the bottom of the body to the regions outside of the classifying zone,

to wit, through the discharge openings or area Il leading from the classifying zone.

Now assuming thecase where the supply of pulp is relatively continuous, the pulp vis continually fed from the hopper over the distributing Lplate where it is suitably discharged into the classifying zone. is an accompanied loading of solids into the liquid-solids body with the result that there is an increase in density of the entire liquid-solids 'body within the classifying zone and a consequent increase in hydrostatic head of the material at the bottom or lower portion of the liquid-solids body in said zone. The upllow or pressure water through and from the orifices of the flow constrlction member and thence into the liquidsolids body has not beenl interrupted and the mobile characteristics oi' the body are continued f and maintained because of the oscillatory movement which is continuously imparted to the flow constriction member. This results in the continual or ever-changing position of the solids in the mobile mass within the liquid-solids body whereby the finer particles of the solids are released andpassed upwardly and ultimately outwardly as tlnes suspended in the liquid overilowing the high slimes weir. At the same time because of the increase in density and consequent increased hydrostatic pressure the pressure at the bottom of the bed becomes suilicient to overcome the co t ance whereby' there can and does follow an outflow of the sands, settled solids, or concentrate as they may be called, into and through the Under such conditions there 'the central section Il of the now constriction plate 12|. From the sands receiving space I! the discharged solids. sands or concentrates pass downwardly through sands discharge tube or conduit l5 and ultimately from the classier. In

, respect to the process and apparatus hereof the following features will be noted:

The process involves the establishment of a liquid-solids body which is peripherally defined preferably by a cylindrical marginal wall, and which is defined as to its lowermost limits by a constriction plate yhaving openings leading upwardly therethrough which are distributed relativelyuniformly throughout the area immediately underlying the liquid-solids body. The ow constriction plate is actuated so as to maintain mobile characteristics of the settled sands mass established in the lower portion of the body. The position of the sands in the body or mass is continually or ever changing relative to each otherdue to this back and forth repetitive movement of the constriction plate and the everchanging position of the sands is further aided by the water upilowing into the lower portion of the liquid-solids body. There is a constant outflow of slimes, to wit, liquid with fine or less readily settleable solids suspended therein. over a high slimes overilow and a relatively simultaneous or consequent outflow of sands or concentrate particularly when the density or hydrostatic head within the body is suillciently great to force the sands or-settled solids outwardly through discharge area provided therefor against a constantly maintained back pressure.

The constant back pressure is sufllciently great to insure the retention in the liquid-solids body of 'the mobile characteristics thereof even when there has been a cessation of feed thereto. There is a hutch compartment or receiving space below the apertured constriction plate. There is pro-` vided means 'for removing from the hutch compartment or chamber such products or fine solids as may havebeen passed downwardly through whole with the result that the upper portions of tbackpressureorliquidbebsolids discharge area or openinl as 4| 91ml- 1I the liquid-solids body remain at a uniform level in a relatively Aquiescent state in so far as the reciprocating movements of the constriction plate or member are involved. The Vhoriiaontal reciprocation of the flow constriction member or flow oonstricting member, as it may be called. also effects akshearing action on the liquid upilowing therefrom; it serves as a flow distribution or flow distributing member whereby the upilowing liquid is disposed relatively uniformly within and throughout the solids of the liquidsolids body. all of which aids in eliminating and avoiding pulp banks, dead spots, local boiling or pot holes in the liquid-solids body.- The portion of the structure which donnes the inner and outer margins or limits of the liquid-solids body are cylindrical or circular in .cross section and/are concentric with respect to each other and with the axis about which they oscillate. 'Reliance is made upon the physical phenomenathat even though the circular body-defining members have repetitive back and forth movement they do not vimpart or allcw any lateral-nvm.,l horizontalso mounted andof a character that they hold the liquid-solids body in and restrain it against any lateral bodily movement even though the apertured ow constriction member or plate underlying the body has repetitive movement imparted` thereto.

The upfiow of liquid'under pressure from the flow distributing openings of the constriction plate into the lower portions of the body of liquid overlying the constriction plate must be in quantities and at velocity rates for realizing the classifying and fractionatingoperation and it must be sufficiently low to avoid pot holes orboiling in the body. The arrangement of the flow distributing openings in the constriction -plate is preferably practically uniform throughout more particularly that portion of the flow distributing' member which is immediately below the liquidsolids body in' the classifying zone and the repetitive movement of the fiow constriction plate is for the purpose of effecting an intimate dispersion of the upflow liquid in and throughout the`solids of the liquid-solids body and for 1mparting and maintaining the mobile characteristics of the massof heavier settledv solids and=ff-\f= the liquid containing the same whereby they automatically hydraulically 'pass from the interior of the classifier zone to the exterior thereof against the constantly maintained vback pressure as and when the hydrostatic head or pressureA within the classifying zone is sufficiently great yincident or consequent to the feeding of pulp to and loading of the liquid-solids body particularly with the more readily settleable type oi v solids. The upflow of liquid from the perforated plate into the liquid-solids should be at a rate prising maintaining conditions of hydraulicl teeter in a liquid-solids body. feeding thepulp j to the upper portion of a liquid-solidsbed, mar-l ginally defining said bed against lateral bodily movement, defining the lowermost limits of said bed by a level constriction plate having numerous liquid discharge orifices disposed substantially the liquid discharge openings of said constric- I tion plate upwardly into `the bed at uniform relatively 'non-pulsatingvelocity rates sumciently high for the classifying or fractionating operation but below rates apt tocreate eddying therein, avoiding imparting repetitive vertical movements to said constriction plate but continually imparting to said lconstriction lplate repetitive horizontal oscillatorymo'vements of relatively limited arcuate range about a vertically extending axis whereby the settled solids of the bed as well as teetering solids thereof constitute a mobile mass, overflowing as slimes liquid with certain of the lighter or finer solids therein marginally from the normal level of the liquid, imposing a relatively yieldable but maintained backpressure constantly acting in opposition to the outward passage of sands into, through and from the solids discharge area and functioning to preclassifier for fractionating pulp embodyingreadily settleable sands and solids that are less readily settleable. a container for a mixed liquidsolids body including inner and outer body defining annular walls and a bottom flow distributing member with flow discharge orifices distributed throughout the area immediately underlying said body which is located so that it surrounds the inner annular walll and which is marginally limited by the outer -marginal wall, means for supplying water under pressure to the underside of said flow distributing member for forcible delivery upwardly into and from said discharge ori- Y fices, means for imparting to said flow distributing member. repetitive horizontal movements to further the distribution of water within the b ed and'forimparting movements vfavorc able Ato the maintaining of the settled solids in the body in a mobile state and at the same time avoiding imparting to the flow distributing member any repetitive up and down movement whereby to avoid bodily raising or lowering of the mixed liquid-solids body,` a high snmes weir functioning at constant elevationl that is the same as the normal operative level of the body and over which liquid with lighter solids suspended therein continually pass as eilluent from the classifier, and, settled solids outflow means including a sands which sands move and outflow as they accumuthroughout the area thereof that is immediately l below the marginally defined bed, providing a solids discharge area leading from the lower portion of said bed'to regions spaced therefrom,

continually passing liquid under pressure from' late during the normal feeding of pulp to thebody to overcome the continuously acting back pressure, the back pressure being suillcient to insure retention of enough' sands in the body to maintain an individually mobilized mass of settled sandsin the body.-

3. ln operative combination in a continuous classifier for fractionating pulps bearing suspended solids in the form of readily settleable sands and finer solids which are less readily settleable, means providing acircular wall for mar-v ginally confining/a mixed liquid-solids body and for 'retaining said body against lateral bodily movements, a horizontally-movable constriction plate providing a levelupper surface of constant elevation disposed below said wall `so as to def fine the lowerrnost limits of the bodyand provided vwith flow-discharge orifices immediately below the body, means for supporting the flow constriction plate whereby it can have imparted thereto repetitive horizontal oscillatory movements about a vertically-extending axis concentric with the circular wall and without having bodily up or down movements for thereby avoiding any bodiiy raising and lowering ofthe mixedV orices of the plate intothe overlying liquid body and under pressure sumcient to maintain conditions of hydraulic teeter in the body, marginal outflow means having a circular high overflow section that rises to the normal operative surface levelof the body while concentric with respect to said vertical axis and by which liquid with certain of the finer solids continually pass as slimes from the body, means for horizontally oscillating the constriction plate relative to the liquid body forL thereby furthering the'distrlbution of water into and through said body which is normally ever changing and for imparting tangential movement to the settled solids immediately over and which from time to time may engage the upper lsurface of the flow constriction plate, solids-discharge means leading from the lower interior portion of the body-holding section and provided with a baffled circular low sands overflow weir of normal constant elevation and concentric with said vertical axis for permitting the automatic outflow of heavier solids from the lower portion of the liquid body consequent to increase in the density of the body incident to the continuous feeding oi' pulp to the body, and means for passing hutch products from the lower interior. portion of said pressure chamber.

4. A continuous classifier for metallurgical pulp and the like comprising in operative combination a container functioning at a constant elevation for a maintained liquid-solids body having circular confining walls with a marginal.l

slimes overflowweir at the upper portion thereof normally functioning at constant elevation and a bottom constriction plate with flow discharge orifices distributed throughoutthe area immediately below the body withinsald circular confining walls and Aalso normally functioning at constant elevation, a casing member providing a hutch compartment therein at the underside of the constriction plate, supporting bearings by which the container is supported to permit oscillatory movement of limited arcuate range in horizontal paths about a vertically-extending axis but so that no vertical movement is imparted to the container, means for supplying water under adjustable pressure to the interior of the hutch compartment and for thereby forcibly .delivering 22,546 portion of the container and having a settled solids overflow welr normally at constant elevation and at elevation lower than that of the slimes overow weir.

5. An apparatus of the class described comprising in operative combination a liquid holding structure embodying an apertured horizontallyextending flow constriction and distributing member. means for imparting reciprocatory horizontal movements thereto withoutimparting up or down movements thereto, means for supplying water constantly for delivery relatively uniformly upwardly from the apertured portion of the member into the region immediately above the same, a marginal wall extending upwardly to a point above the apertured member and providing with the latter a classifying space wherein a liquid-solids body is located and normally maintained while undergoing treatment for the fractionating of the solids into different groups of fines and sands and which marginal wall is disposed so as to hold said body against lateral bodily displacement, a fines overflow weir of normal constant elevation that determines the normal level of the liquid body which is laterally confined by the marginal wall, and means leading upwardly from the lower portion of said liquid-solids body and providing a sands overflow weir of normal constant elevation and disposed at an elevation lower than that of the first mentioned weir whereby as the apparatus normally functions sands will be hydraulically passed from the lower portion of the body and intimately will be delivered over the lower sands overflow weir.

8. The process of classification comprising feeding a stream of solids in liquid suspensionvent an outward passage towards the low WeirV of liquids except such as pass under said baille; continually imparting horizontal oscillatory movements to the plate in a manner whereby the plate has repetitive back and forth horizontal anguiar movements relative to the overlying pool and in a manner whereby there'is avoided imparting of any up or down movement to the plate;

continually flowing over the top edge weir a selected fraction of suspended solids from the zone; maintaining in the pool at elevation lower than that of the top edge weir and contiguous to the plate a bed of solids fn mobile suspension: continuously effecting passage under the bame and water into the flow discharge orifices and upover the low welr a selected fraction of said suspended solids by supplying to and distributing throughout the lower portion of the zone upflow currents of liquid passing thereto through the perforations'in the plate at a rate for maintaining teeter conditions within the pool; and controlling the character of solids selectively passing to the respective fractions principally by the vertical distance between the elevations of the top edge and low overflow weirs.

7. Classification apparatus comprising a tank, a substantially horizontal perforated plate dividing the Atank into an upper and a lower compartment, the upper compartment being adapted to serve as a classification zone for holding a pool of liquid having suspended solids some .of which settle as a subnatant bed overlying the plate, feed means for the upper compartment, means for supplying Vliquid constantly under pressure through the perforations of the plate: the compartment below the plate being adapted to function for holding liquid under pressure, means for supporting the' plate at constant elevation but which permits horizontal movement of the plate, means for imparting repetitive horizontal oscillatory movements to the plate about a verticallyextending axis, a high annular overflow Weir edge for the upper compartment and a low annular weir edge for the lower compartment, baille means functionally disposed between said weirs and extending downwardly towards the plate into a' region proximate the low weir adapted to provide at the lower end thereof a transfer passageway leading towards the low weir while restricting flow of liquid from the compartment past the low Weir, said weirs and baille being concentrically disposed with respect to the axis about which the perforated plate oscillates.

8. Classification apparatus comprising a cham- Y of the bath, means providing an'upow passage for sands, a sands overflow edge weir of substantially constant elevation whose upper edge is sub-I stantially lower than that of the elevation of the edge of the fines Weir, means for horizontally oscillating the plate about a vertically extending axis but for limited arcuate range forY imparting mobility to a submerged bed of settled sands in the lower portion of the bath but at the same time avoiding imparting any substantial vertical bodily rribvement to the plate, and means for l passing water at relatively constant velocity upwardly through the perforations of the plate and through the mobilized bed of sands under pressure sumcient to cause classifying teeter in the bath as well as to upiiow classified fines over the lines overflow weir while permitting settling of classified sands td the mobilized bed of sands, the differential in elevation as between the high fines weir and the lower sands weircontrolling the height of the vmobilized bed of sands whereby newly classied sands therein cause a corresponding displacement of sands through said passageway and over the sands weir.

9. A method of classiiication which comprises maintaining at relatively constant elevation and against lateral displacement a classifying bath of suspended solidsyhaving a horizontally movable perforated plate normally maintained at constant elevation, distributing a feed of classiable solids applied to the bath substantially at the surface thereof: balancing the bath containing a bed of settled solids disposed adjacent the plate with an adjustable height of classined -sands and water outside of the bed: continually upilowing water at suilicient pressure through the perforationsi., of the plate and through the bed of sands whereby to effect a classlcation of the fed solids at' the desired cut ,of sizes in a hydraulically mobilized portion of the bath above the bed of sands Yand to overflow classied suspended lines therefrom overand past a high weir edge of relatively constant elevation; horizontally oscil'- lating the plate relative to the bed through a limited arcuate range about a vertically extend-A ing axis for 'contributing to the maintenance' of the bed of sands in individually mobilized condition; and continually discharging from said column beneath a baille and over a low overflow weir of relatively constant elevation sands in quantity equal to newly classified sands settling to the bed as a result of the classification action thereupon.

ARTHURA WILLIAM FAHRENWALD. 

